Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile needs no restatement. The description adds value beyond them by disclosing what the response contains, notably that the body is plain text and that audio url and sources are included — meaningful since no output schema exists. It stops short of noting failure behavior (e.g., unknown slug) or size/length characteristics of the body.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The core sentence is front-loaded with the verb and resource and packs the return-field list efficiently with no filler. The second sentence is a short compliance disclaimer that serves a domain purpose but is not about tool selection or invocation.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a single-parameter read tool with full annotation coverage and a fully documented schema, the definition is nearly sufficient; listing the returned fields compensates for the absent output schema. The remaining minor gap is that an agent is not told what happens when the slug does not exist or how to obtain a slug other than via the schema's mention of list_notes.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and the single slug parameter is documented with a concrete example (xpub-is-not-a-public-key) plus provenance (from list_notes). The description only repeats "by slug" and adds no format, case-sensitivity, or validation detail. Baseline 3 applies when the schema carries the parameter documentation.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

"Get one note by slug" states a specific verb (get) and resource (note) with single-item scope, and enumerates the returned fields (title, description, publishedAt, tags, url, audio url, sources, body). It implicitly contrasts with list_notes/search_content through the word "one," but never names those siblings explicitly, so differentiation is inferred rather than stated.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: an agent can infer this is the retrieval step after list_notes or search_content surfaces a slug. There is no explicit when-to-use, when-not-to-use, or named alternative such as list_notes for enumeration. The trailing "Education only, not financial advice" line is a content disclaimer, not invocation guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.